Solderless connector for insulated electrical conductors

ABSTRACT

Solderless connector for electrically connecting the conducting cores of insulated electrical conductors, and particularly the plastic-insulated conductors of telephone cables. The connector includes a conical contact pin having a series of sharp edge contact points in the form of annular ridges spaced along and projecting from the periphery of the pin. A cylindrical shell having a closed end and an open end, extends about the contact pin. The contact pin abuts the closed end of the shell and tapers toward the open end of the shell. The shell is made from a polymerized plastic material which shrinks under the influence of heat and sets to its shrunk condition as it cools. The open end of the shell has an inturned lip containing a plastic ring to the interior open end portion of the shell, which melts as it is heated. A series of insulated conductors are inserted into the shell. As the shell is heated it will shrink and engage the conductors with the sharp-edged contact points of the contact pin with sufficient force to force the contact points or ridges through the insulation into contact with the conducting cores of the conductors. The plastic ring at the same time will melt as the shell is heated and seal the conductors to the shell.

I United States Patent [151 3,636,238 Biebach 1 Jan. 18, 197 2 [54]SOLDERLESS CONNECTOR FOR INSULATED ELECTRICAL Primary Examiner-DarrellL. Clay CONDUCTORS Attorney-Hill, Sherman, Meroni, Gross & Simpson [72]Inventor: Erwin Biebach, Soecking, (near Starberg), 57] BST GermanySolderless connector for electrically connecting the conduct- Asslgneeislemfms Aktlengesellschafl, Bel'lm and ing cores of insulated electricalconductors, and particularly Mumch Germany the plastic-insulatedconductors of telephone cables. The con- [22] Filed; June 25, 1970nector includes a conical contact pin having a series of sharp edgecontact points in the form of annular ridges spaced along [21] PP N0549,748 and projecting from the periphery of the pin. A cylindrical shellhaving a closed end and an open end. extends about the [30] ForeignApplication P i i D m contact pin. The contact pin abuts the closed endof the shell and tapersto'ward the open end of the shell, The shell ismade y 1969 -"Q 19 9 from a polymerized plastic material which shrinksunder the influence of heat and sets to its shrunk condition as itcools. 52 U.S.Cl. ..174 s7, 29/628, 174 010. 8, The open end of the She"has an inmmed lip containing a 174/84. 339/97 R plastic ring to theinterior open end portion of the shell, which [51] II!!- CL' .;H0 2g15/08 melts as it is heated A series f insulated conductors are i FieldOf Search 1 8, R, Serted into the shell. As the she is heated it Shrinkand 339/97 95 R; 29/628 gage the conductors with the sharp-edged contactpoints of the contact pin with sufi'icient force to force the contactpoints [56] References Clted or ridges through the insulation intocontact with the conduct- UNITED STATES PATENTS ing cores of theconductors. The plastic ring at the same time will melt as the shell isheated and seal the conductors to the 3,243,211 3/1966 Wetmore..l74/DIG. 8 Shell. 3,320,355 5/1967 Booker ...174/DIG. 8 3,480,72311/1969 Golden 174/84 C X 7 Claims, 3 Drawing Figures In IIIPATENIEDJmsm 3636238 uu-m j INVENTOR flaw/77 B/eb ac/i B ATTYS.

BACKGROUND AND OBJECTS OF THE INVENTION Solderless connectors forelectrical conductors, such as plastic-insulated telephone cables haveheretofore been used for connecting the cables without stripping theinsulation from the cables. An illustrative form of connector is shownand described in US. Pat. No. 3,064,072 and termed a B wire connector.The connector consists of an outer plastic shell, an innermost metalshell within the plastic shell and an additional metal shell surroundingthe innermost metal shell. The inmost metal shell is punched at severalplaces to produce sharp-edged teeth projecting from the inner peripheryof the shell which penetrate into the insulation of the conductors wheninserted into the shell. The inmost shell is pressed into engagementwith the conductors by means of a tool. With such connectors the metalshells are made from a springy metal which tends to swell after acertain period of use after deformation of the shell. This swelling ofthe deformed shells, therefore, interfers with the reliability of thecable-core connection.

By the present invention, I cure the deficiencies of previous solderlessconnectors by surrounding a contact pin with a shell made from amaterial shrinking under the influence of heat and maintaining its setwhen cooled and thereby pressing the electrical conductors inserted inthe shell into engagement with the contact pin with sufficient force tocause sharp contact ridges or points on the contact pin to penetrate theinsulation of the conductor and make good contact therewith. The shellis preferably made from heat-shrinkable polymerized plastic materialwhich looses its flowing ability when heated and cooling, and therebymaintains firm contact pressure against the conductors even in placeswhere there is a wide variation in temperature.

A principal object of the present invention is to provide an efficientand reliable connector for insulated electrical conductors applicable toa series of conductors and requiring no mounting tools to make theconnection.

Another object of the invention is to provide a connector for electricalconductors in which the reliability of the connection does not dependupon a careful mounting of the connector on the conductors.

Another object of the invention is to provide a simplified connector forelectrical conductors in which a cylindrical shell encircles a conicalcontact pin tapering inwardly toward an open end of the shell, tofacilitate the insertion of a series of electrical conductors into theshell and along the pin, and in which the shell shrinks to the form ofthe contact pin as heated.

A further object of the invention is to provide a self-sealing connectorfor connecting a series of conductors in conducting relation relative toeach other in which a contact pin is encircled by a shell and the shellhas an open end spaced from the contact pin having a sealing ring ofthermoplastic material carried thereby which melts upon the shrinking ofthe shell and seals the conductors against the moisture and otherharmful influences.

Still another object of the invention is to provide a connector for aseries of electrical conductors arranged with a view toward utmostsimplicity in construction and operation and efficiency in makingcontact between two conductors without the use of the tools heretoforerequired for such connectors.

Other objects, features and advantages of the invention will be readilyapparent from the following description of a preferred embodimentthereof, taken in conjunction with the accompanying drawings, althoughvariations and modifications may be effected without departing from thespirit and scope of the novel concepts of the disclosure.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional viewtaken through a connector constructed in accordance with the principlesof the present invention, showing the contact pin in solid.

FIG. 2 is a longitudinal cross-sectional view taken through theconnector, with the contact pin in solid and illustrating the form ofthe shell, as the shell encircling the contact pin is shrunk under theinfluence of heat; and

FIG. 3 is a crosysectionalview taken substantially along line A-B ofFIG. 2.

DESCRIPTION OF PREFERRED EMBODIMENT OF THE INVENTION In the drawing, Ihave shown a connector for a series of electrical conductors including ashell 1 of a generally cylindrical form having a closed end 7 andextending about a contact pin 4 extending axially along the shell fromsaid closed end toward an open end 6 of the shell.

The shell 1 is made from a material which will shrink under theinfluence of heat and will maintain its set as it cools and may be madefrom several well-known forms of polymerized plastic materials whichwill shrink when heated and lose their flowing ability, and will thenset to a shrunk form. Shrinking of the plastic shell thereby providesradially inwardly extending shrinking forces, effective about thecircumference of the shell, and pressing the insulated conductorsagainst sharpedged contact points 5 of the contact pin 4.

The closed end 7 of the shell is formed by tapering the rear end of theshell and closing the end of the shell by means of a suitable sealingmaterial 2 which may also seal the contact pin 4 to the shell. The openend 6 of the shell is formed by turning the end of the shell inwardly asindicated by reference numeral 8, to form an opening 3 in the shell ofsmaller diameter than the largest diameter of the contact pin, andaccommodating the insertion of insulated conductors 9,10 and 11 into theshell to extend along the contact pin 4.

At the open end portion of the shell, and abutting the inside of theinturned end portion 8 thereof, is a thermoplastic ring 12 which meltsas the shell is heated to a shrinking temperature and seals theconductors 9,10 and 11, and the interior of the shell, against moistureor other harmful influences, and anchors the conductors to the shell.

The contactpin 4 is of a generally conical form and converges toward theopen end of the shell. The end of said contact pin facing the open endof the shell, terminates into a rounded apex, enabling the conductors9,10 and 11, or any other number of conductors to readily be inserted inthe shell along the contact pin 4 and into engagement with a series ofsharp-edged cutting rings 5 spaced along and projecting from theperiphery of the shell,

' The contact pin 4 is made from a metal having good electricalconducting qualities and having the sharp-edged cutting ridges 5 spacedtherealongjan'd herein shown as fonned integrally therewith. The cuttingridges 5 are V-shaped in cross section and terminate into sharp peaksextending about the contact pin, which are sufficiently sharp to cutinto the insulation of the conductors and make good contact with theconducting cores thereof as the shell is heated and shrinks to press theconductors against the cutting ridges 5.

Three conductors 9, 10 and l 1 are shown herein for illustrativepurposes although it should be understood that any desired number ofconductors may be provided. Said conductors may have copper or otherconducting cores or wires providing good conductors of electricity andpreferably covered by plastic insulation, which will soften as the shellis heated and facilitate the cutting the insulation by the sharpedgedcontact ridges, as the shrinking shell presses the conductors intoengagement with the sharp-edged cutting ridges 5.

In making an electrical connection the conductors 9,10 and 11, or anyother number of conductors are inserted into the shell from the open end6 thereof along the contact pin 4, close to the closed end of the shell,as shown in FIG. 2. The shell is then heated by a suitable heat sourceto a temperature in the range of 250 C., it being understood that as theshrinking shell is heated, the temperature range may vary, since, theshell is made from a polymerized plastic material, the material loosesits flowing ability as it shrinks and cannot be melted further. Theshrinking of the shell by heat provides shrinking forces which areeffective all around the circumference of the shell and thereby pressthe conductors 9, and 1 1 against the sharp-edged contact ridges of thecontact pin, and displace the insulation of the conductors by means ofthe sharp-edged ridges, which cut into the metal cores of the conductorsby the force of displacing the insulation thereof and thereby make agood electrical connection with the cores of the conductors, as shown inFIGS. 2 and 3. The plastic shell then loses its flowing properties as itcools, and effects continuous pressure onto the conductors, to providegood electrical contact between the conductors, even under largefluctuations in temperature.

As the shell shrinks, the thermoplastic sealing ring 12 will melt andseal the interior of the shell and the conductors against moisture andother harmful influences on the outside of the shell. The melting of thesealing ring further anchors the conductors within the shell and holdsthe conductors from being pulled from the shell, in addition topositively sealing the open end of the shell.

It should be understood from FIG. 2 that the shell when shrinkinggenerally conforms to the conical form of the contact pin and positivelyretains the conductors and contact pin to the shell, but providesundistorted opposite ends of the shell, retaining the conductors andcontact pin to the shell and readily fitting in small spaces.

I claim as may invention:

1. A solderless connector for insulated electrical conductors andparticularly the plastic-insulated conductors of telephone cablescomprising a generally cylindrical shell made from a heat-shrinkableplastic material, settable to its shrink form when cool and having,

at least one open end,

a contact pin contained within said shell and extending concentricallyof and spaced from the interior wall of the shell and having a pluralityof sharp contact cutting edges extending from its external periphery andspaced radially inwardly from the interior wall of the shell,

said shell adapted to exert radially inward force on the insulatedconductors disposed between said pin and said shell when shell is heatedand shrunk and pressing the conductors against said contact cuttingedges with said contact cutting edges cutting through the insulation ofthe conductors and making a good electrical connection with theconducting cores of said conductors and retaining said conducting coresinto engagement with said contact cutting edges.

2. The solderless connector of claim 1, wherein the shell is generallycylindrical in form, the contact pin is generally conical and has aconverging end facing the open end of the shell, and the shell isadapted to shrink and generally conform to the form of said contact pinand maintain the general form of said contact pin when shrunk.

3. The solderless connector in claim 2,

wherein the shell has one closed end and an opposite intumed endterminating into an opening smaller than the larger outer diameter ofthe contact pin, to retain said contact pin to said shell andaccommodate the insertion of electrical conductors along said contactpin through the open end of said shell.

4. The solderless connector of claim 3, wherein the sharp contactcutting edges are in the form of parallel sharp annular ridges spacedalong said contact pin.

5. The solderless connector of claim 4, wherein a sealing ring extendswithin the open end of the shell along the inturned end thereof and isadapted to melt to seal the open end of the shell and conductorsextending thereinto when said shell is shrunk.

6. The solderless connector of claim 2, wherein the sharp contactcutting edges are in the form of a plurality of parallel spaced sharpannular ridges spaced along said contact pin and extending thereabout.

7. The solderless connector of claim 6, wherein a plastic sealing ringextends within the open end of the shell and radially inwardly from theinterior wall thereof and is adapted to melt to seal the conductors tosaid connector when the shell is permanently shrunk.

* III

1. A solderless connector for insulated electrical conductors andparticularly the plastic-insulated conductors of telephone cablescomprising a generally cylindrical shell made from a heatshrinkableplastic material, settable to its shrink form when cool and having, atleast one open end, a contact pin contained within said shell andextending concentrically of and spaced from the interior wall of theshell and having a plurality of sharp contact cutting edges Extendingfrom its external periphery and spaced radially inwardly from theinterior wall of the shell, said shell adapted to exert radially inwardforce on the insulated conductors disposed between said pin and saidshell when shell is heated and shrunk and pressing the conductorsagainst said contact cutting edges with said contact cutting edgescutting through the insulation of the conductors and making a goodelectrical connection with the conducting cores of said conductors andretaining said conducting cores into engagement with said contactcutting edges.
 2. The solderless connector of claim 1, wherein the shellis generally cylindrical in form, the contact pin is generally conicaland has a converging end facing the open end of the shell, and the shellis adapted to shrink and generally conform to the form of said contactpin and maintain the general form of said contact pin when shrunk. 3.The solderless connector in claim 2, wherein the shell has one closedend and an opposite inturned end terminating into an opening smallerthan the larger outer diameter of the contact pin, to retain saidcontact pin to said shell and accommodate the insertion of electricalconductors along said contact pin through the open end of said shell. 4.The solderless connector of claim 3, wherein the sharp contact cuttingedges are in the form of parallel sharp annular ridges spaced along saidcontact pin.
 5. The solderless connector of claim 4, wherein a sealingring extends within the open end of the shell along the inturned endthereof and is adapted to melt to seal the open end of the shell andconductors extending thereinto when said shell is shrunk.
 6. Thesolderless connector of claim 2, wherein the sharp contact cutting edgesare in the form of a plurality of parallel spaced sharp annular ridgesspaced along said contact pin and extending thereabout.
 7. Thesolderless connector of claim 6, wherein a plastic sealing ring extendswithin the open end of the shell and radially inwardly from the interiorwall thereof and is adapted to melt to seal the conductors to saidconnector when the shell is permanently shrunk.